Large swathes of deltas along China's shore are threatened by erosion as sea levels rise, oceanic authorities said.

"A total of 2,500 square kilometers of land at Laizhou Bay gave way to sea water last year, when the waterfront moved 45 kilometers inland at the furthest," said Wang Shicheng, an oceanic official in the eastern Shandong Province on Friday.

A growing area of the low-lying shoreline of Laizhou Bay off the Bohai Sea has been seriously salinized, rendering it unsuitable for farm produce or fish breeding, said the deputy head of the Shandong Oceanic Administration.

According to the 2007 Sea Level Bulletin released by the State Oceanic Administration earlier this month, the rises in sea levels along China's shores have gained speed in recent years, as climate change intensifies. Meanwhile, coastal areas in north and south China had more frequent abnormal temperature rises and oceanic disasters.

Wang said that the water temperature of China's Bohai Sea and Yellow Sea rose by 1.1 degree and 1.8 degree Celsius, respectively, year-on-year in March last year, while the sea level for each surged by 0.102 meter and 0.148 meter.

"High tides generated by the strongest wind storm in 38 years rolled over 2 meters high on the coast. The tide flush-in induced direct economic losses of 2.1 billion yuan," said Wang, a prominent Chinese oceanographer. The damage was equivalent to about 291 million U.S. dollars.

China's total sea level rise in the past 30 years was 0.09 meter on average. Among all coastal areas, the northern city of Tianjin, which lies along the Bohai Sea, saw the fastest speed of sea level rise, with a total increase of 0.196 meter, while Shanghai, in the east, had a rise of 0.115 meter, according to the Bulletin.

The State Oceanic Administration has warned Tianjin that its coastal embankment is not solid enough to withstand strong tides, as a result of the continuous rise of the sea level.

Wang said that the melting of polar glaciers due to global warming had been recognized as the direct cause of global sea level rises.

"The sea level off Shandong would continue to rise by 0.029 meters in the next decade," said Wang.

The administration expects that nationally, the sea level along China's coast would rise 0.032 meter on average in the next decade.

On the southern coast, many freshwater reservoirs have been contaminated by sea water, and large areas of fertile mangrove disappeared due to shoreline erosion and offshore pollution.